In an industrial laser robot having a robot unit, a laser beam emitted by an external laser generator is guided through a laser beam conduit to the laser beam inlet of the robot unit, and then the laser beam travels along a laser beam pathway formed within the robot unit to a laser beam projecting unit mounted on a robot wrist joined to the extremity of the robot unit. The laser beam projecting unit projects the laser beam on a workpiece under the control of a robot control unit for laser beam machining by the utilization of the energy of the laser beam, such as laser beam cutting, laser beam welding and laser beam deflashing.
In a laser robot of the above-described kind, it is essential to the use of the high energy of the laser beam for laser beam machining that the laser beam projected by the laser beam projecting unit is focused on a desired point on a workpiece. Accordingly, it is impossible to achieve exact laser beam machining unless the laser beam projected by the laser beam projecting unit is continuously focused on desired points on the workpiece during the continuous laser beam machining in which the joints of the laser robot are controlled for specified motions by a robot control unit according to a control program taught beforehand and stored in the robot control unit.
During the laser beam machining, the laser beam ducted through the external laser beam conduit to the robot unit is deflected by reflecting mirror units disposed on the respective axes of motion of the joints so as to travel along the laser beam pathway internally extending through the robot unit to the laser beam projecting unit disposed at the extremity of the robot unit. Accordingly, it is essential to focusing the laser beam projected by the laser beam projecting unit on the workpiece that the laser beam travels within the robot unit along the respective axes of motion of the joints. Namely, the beam axis of the laser beam must be in a coincident relationship with the respective axes of motion of the joints.
To this end, the beam axis of the laser beam of the laser robot must be adjusted in many stages of production thereof including a manufacturing stage and an assembly stage, before shipping of the laser robot from the factory, when installing the laser robot in a site of operation, when inspecting the laser robot for routine maintenance work and when transferring the laser robot from one place to another within the operation site.
When adjusting the beam axis of the laser robot, a visible, low-energy laser beam such as a ruby laser beam is used instead of the high-energy machining laser beam such as a carbon-dioxide gas laser beam.
A method of adjusting the beam axis of a laser robot and an apparatus for carrying out the same are disclosed in International Application No. PCT/JP91/101546.
The known method of adjusting the beam axis of a laser robot, using a visible laser beam, however, has a disadvantage that the method requires a comparatively expensive beam axis adjusting apparatus including photodetectors and the like, and comparatively difficult adjusting work.